GANGLIA. 427 



spinal ganglia of the frog, von Lenhossek (95) found centrosomes 

 surrounded by a clear substance (centrospheres). The entire struc- 

 ture lay in a depression of the nucleus and contained more than 

 twelve extremely minute granules (centrosomes), which showed a 

 staining reaction different from that of the numerous concentrically 

 laminated granules present in the protoplasm. This observation is 

 interesting in that it proves that centrosome and sphere occur also 

 in the protoplasm of cells which have not for a long time under- 

 gone division and in which there is no prospect of future division. 



Sympathetic Ganglia. The ganglia of the sympathetic ner- 

 vous system comprise those of the two great ganglionated cords, 

 found on each side of the vertebral column and extending from its 

 cephalic to its caudal end, with which may be grouped certain cranial 

 ganglia having the same structure, namely, the sphenopalatine, 

 otic, ciliary, sublingual, and submaxillary ganglia ; also three un- 



Fig. 341. Neurone from inferior cervical sympathetic ganglion of a rabbit; methylene- 



blue stain. 



paired aggregations of ganglia, found in front of the spinal column, 

 of which the cardiac is in the thorax, the semilunar in the abdomen, 

 and the hypogastric in the pelvis ; and further, large numbers of 

 smaller ganglia, the greater number of which are of microscopic 

 size and are found in the walls of the intestinal canal and bladder, 

 in the respiratory passages, in the heart, and in or near the majority 

 of the glands of the body. 



The sympathetic ganglia are inclosed in fibrous tissue capsules 

 continuous with the perineural sheaths of their nerve-roots. The 

 thickness of the capsule bears relation to the size of the ganglion, 

 being thicker in the larger and thinner in the smaller ones. From 

 these capsules thin connective-tissue septa or processes pass into 

 the interior of the ganglia, supporting the nerve elements. 



The sympathetic neurones, the cell-bodies and dendritic processes 

 of which are grouped to form the sympathetic ganglia, are variously 



